/*
 * Copyright (C) 2015-2017 Alibaba Group Holding Limited
 */

/*
 / _____)             _              | |
( (____  _____ ____ _| |_ _____  ____| |__
 \____ \| ___ |    (_   _) ___ |/ ___)  _ \
 _____) ) ____| | | || |_| ____( (___| | | |
(______/|_____)_|_|_| \__)_____)\____)_| |_|
    (C)2013 Semtech

Description: Helper functions implementation

License: Revised BSD License, see LICENSE.TXT file include in the project

Maintainer: Miguel Luis and Gregory Cristian
*/
#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
#include "../loramac/utilities.h"

/*!
 * Redefinition of rand() and srand() standard C functions.
 * These functions are redefined in order to get the same behavior across
 * different compiler toolchains implementations.
 */
// Standard random functions redefinition start
#define RAND_LOCAL_MAX 2147483647L

static uint32_t next = 1;

int32_t rand1( void )
{
    return ( ( next = next * 1103515245L + 12345L ) % RAND_LOCAL_MAX );
}

void srand1( uint32_t seed )
{
    next = seed;
}
// Standard random functions redefinition end

int32_t randr( int32_t min, int32_t max )
{
    return ( int32_t )rand1( ) % ( max - min + 1 ) + min;
}

void memcpy1( uint8_t *dst, const uint8_t *src, uint16_t size )
{
    while( size-- )
    {
        *dst++ = *src++;
    }
}

void memcpyr( uint8_t *dst, const uint8_t *src, uint16_t size )
{
    dst = dst + ( size - 1 );
    while( size-- )
    {
        *dst-- = *src++;
    }
}

void memset1( uint8_t *dst, uint8_t value, uint16_t size )
{
  while( size-- )
  {
    *dst++ = value;
  }
}

int8_t Nibble2HexChar( uint8_t a )
{
  if( a < 10 )
  {
    return '0' + a;
  }
  else if( a < 16 )
  {
    return 'A' + ( a - 10 );
  }
  else
  {
    return '?';
  }
}

uint32_t Crc32( uint8_t *buffer, uint16_t length )
{
    // The CRC calculation follows CCITT - 0x04C11DB7
    const uint32_t reversedPolynom = 0xEDB88320;

    // CRC initial value
    uint32_t crc = 0xFFFFFFFF;

    if( buffer == NULL )
    {
        return 0;
    }

    for( uint16_t i = 0; i < length; ++i )
    {
        crc ^= ( uint32_t )buffer[i];
        for( uint16_t i = 0; i < 8; i++ )
        {
            crc = ( crc >> 1 ) ^ ( reversedPolynom & ~( ( crc & 0x01 ) - 1 ) );
        }
    }

    return ~crc;
}

uint32_t Crc32Init( void )
{
    return 0xFFFFFFFF;
}

uint32_t Crc32Update( uint32_t crcInit, uint8_t *buffer, uint16_t length )
{
    // The CRC calculation follows CCITT - 0x04C11DB7
    const uint32_t reversedPolynom = 0xEDB88320;

    // CRC initial value
    uint32_t crc = crcInit;

    if( buffer == NULL )
    {
        return 0;
    }

    for( uint16_t i = 0; i < length; ++i )
    {
        crc ^= ( uint32_t )buffer[i];
        for( uint16_t i = 0; i < 8; i++ )
        {
            crc = ( crc >> 1 ) ^ ( reversedPolynom & ~( ( crc & 0x01 ) - 1 ) );
        }
    }
    return crc;
}

uint32_t Crc32Finalize( uint32_t crc )
{
    return ~crc;
}

